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<title>rename</title>
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<h2 align=center>rename</h2>
<h4 align=center>OS/161 Reference Manual</h4>

<h3>Name</h3>
<p>
rename - rename or move a file
</p>

<h3>Library</h3>
<p>
Standard C Library (libc, -lc)
</p>

<h3>Synopsis</h3>
<p>
<tt>#include &lt;unistd.h&gt;</tt><br>
<br>
<tt>int</tt><br>
<tt>rename(const char *</tt><em>oldname</em><tt>,
const char *</tt><em>newname</em><tt>);</tt>
</p>

<h3>Description</h3>
<p>
The file (or other object) referenced by <em>oldname</em> is given the
name <em>newname</em>, and the name <em>oldname</em> is removed. If
<em>newname</em> already exists, it is removed as well. (The semantics
for removing files and directories described under
<A HREF=remove.html>remove</A> and <A HREF=rmdir.html>rmdir</A>
must be honored.)
</p>

<p>
If <em>newname</em> exists, it must be a directory if and only if
<em>oldname</em> also is.
</p>

<p>
If components of the path prefix of <em>newname</em> do not exist or
are not directories, rename fails. Additionally, <em>oldname</em> and
<em>newname</em> must refer to names on the same filesystem.
</p>

<p>
If <em>oldname</em> and <em>newname</em> are the same file, rename
succeeds and the state of the filesystem is not altered. This is true
even if they are not in the same directory. (POSIX says so. This is
widely considered a bug in POSIX.)
</p>

<p>
Rename must be atomic; no other process on the system should be able
to see the filesystem in a state where both (or neither)
<em>oldname</em> and <em>newname</em> name the file. Additionally, if
the system crashes, at least one name for the file must remain.
(If you are implementing a file system with crash recovery, a crash
during rename must, after recovery, produce a volume where the rename
has either occurred or not occurred; no intermediate states may be
exposed.)
</p>

<p>
If <em>oldname</em> is a directory, <em>newname</em> must not refer to
a subdirectory of <em>oldname</em>, as this would create a (detached)
cycle in the directory tree.
</p>

<p>
Renaming (or overwriting) the <tt>.</tt> or <tt>..</tt> entries in
directories is prohibited.
</p>

<h3>Return Values</h3>
<p>
On success, <tt>rename</tt> returns 0. On error, -1 is returned, and
<A HREF=errno.html>errno</A> is set according to the error
encountered.
</p>

<h3>Errors</h3>
<p>
The following error codes should be returned under the conditions
given. Other error codes may be returned for other errors not
mentioned here.

<table width=90%>
<tr><td width=5% rowspan=13>&nbsp;</td>
    <td width=10% valign=top>ENODEV</td>
				<td>The device prefix of one of the names did
				not exist.</td></tr>
<tr><td valign=top>ENOTDIR</td>	<td>A non-final component of one of the names
				was not a directory.</td></tr>
<tr><td valign=top>ENOENT</td>	<td>A non-final component of <em>newname</em>
				did not exist.</td></tr>
<tr><td valign=top>ENOENT</td>	<td><em>oldname</em> does not exist.</td></tr>
<tr><td valign=top>ENOTDIR</td>	<td><em>oldname</em> is a directory, and
				<em>newname</em> is not.</td></tr>
<tr><td valign=top>EISDIR</td>	<td><em>oldname</em> is not a directory, and
				<em>newname</em> is.</td></tr>
<tr><td valign=top>ENOTEMPTY</td><td><em>newname</em> is a directory, and it is
				not empty.</td>
<tr><td valign=top>EXDEV</td>	<td>The two names are on different
				filesystems.</td></tr>
<tr><td valign=top>EINVAL</td>	<td><em>newname</em> is a subdirectory of
				<em>oldname</em>.</td></tr>
<tr><td valign=top>EINVAL</td>	<td>An attempt was made to rename a
				<tt>.</tt> or <tt>..</tt> entry.</td></tr>
<tr><td valign=top>ENOSPC</td>	<td>The filesystem involved is full.</td></tr>
<tr><td valign=top>EIO</td>	<td>A hard I/O error occurred.</td></tr>
<tr><td valign=top>EFAULT</td>	<td>One of the arguments was an
				invalid pointer.</td></tr>
</table>
</p>

<p>
As with rmdir, attempts to rename with <em>newname</em> equal to
<tt>..</tt> may generate either EINVAL or ENOTEMPTY.
</p>

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